The store, to be established in two vacant storefronts in a shopping plaza at 290 Congress St., will sell local goods to the public, PFC Board of Directors President Daniel Ungier said at a press conference Monday.

Since its founding in 2007, the PFC has offered a buying service that allows its member-owners to order items online and pick them up at the PFC warehouse, nearby at 56 Hampshire St. To become a member, individuals purchase a $100 share of the co-op; they must also work a few hours each month at the co-op.

The service had sales of more than $200,000 in 2012. But the new, 3,000-square-foot store will allow non-members to "shop local" too.

"This will be a full-service grocery store, open to anyone," Ungier said, noting that the site is easily accessible by bus, offers parking, and is a short walk from Bayside and other areas of the peninsula.

The PFC will hire 20 employees to staff the store, and is looking for a general manager. The co-op plans to partner with Portland Adult Education to fill some of the positions with new residents.

About 100 Maine farmers and merchants will stock the store with produce, meat, dairy goods, coffee, beer and wine, and other items, which will be sold at competitive prices, according to Ungier.

While the store will be open to the public, members will receive discounts and rebates when it earns a profit. To support the store opening, the PFC is hoping to sign up another 1,000 members in coming months.

On Monday, Mayor Michael Brennan said he signed up over the weekend.

"I'm looking for a significant return on my investment as a member," he said with a laugh.

Brennan noted that more than 80 percent of food sold in Maine is imported from outside the state. The result is "food insecurity": Mainers risk going hungry because of price increases and other disruptions in the food supply chain. In addition, the state's reliance on food imports drives use of fossil fuels and does little to stimulate the local economy.

The mayor, who is leading an initiative to increase the use of locally produced food in public schools, called the store "a great new venture, a great new enterprise within the city of Portland.

"The (co-op store) will allow us not only to provide healthy food, but to reduce our carbon footprint and to make us food-secure," Brennan said.

Another fan of the new store is Sarah Wiederkehr, who produces dairy products for the co-op at her farm in Freeport.

"I'm super-excited," she said. "This is going to be a boon for the city, for consumers, and for producers."